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Finding the Fourth Proportional to 121.76, 168.04 and 87.28

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Solution

The fourth proportional to 121.76, 168.04 and 87.28 is: 120.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.76 : 168.04 = 87.28 : x
  2. Step 2: Convert to fraction form
    121.76/168.04 = 87.28/x
  3. Step 3: Cross multiply
    121.76x = 168.04 × 87.28
  4. Step 4: Simplify right side
    121.76x = 14,666.53
  5. Step 5: Solve for x
    x = 14,666.53/121.76
  6. Step 6: Final answer
    x = 120.45

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.